Filters are useful in a variety of devices. For example, filters are often used in electrical or optical equipment. An air pressure differential between the interior and exterior of a housing containing the equipment can be produced as the electrical or optical equipment heats and cools. Often the housing includes a vent or breather hole to allow airflow that equalizes the pressure. A filter is typically provided over the vent to reduce the flow of contaminants into and/or out of the housing.
Computer disk drives, and in particular, hard disk drives, are one example of a device that uses filters in this manner. Disk drives are sensitive to moisture, chemical contamination, and particulate contamination, particularly, as the drive heads become smaller and aerial densities increase. Chemical contaminants, such as hydrocarbons and acid gases, can condense onto a disk and degrade the head/disk interface and/or corrode the heads. Particulate contaminants can lead to stiction and can cause read/write errors and head crashes.
Therefore, a need exists for filters that provide beneficial removal of particulate and chemical contaminants.